Modern medicine offers several primary ways to treat breast cancer, including surgery, radiation, chemotherapy and anti-estrogen treatments. Ongoing investigations of immunotherapies may lead to their wider use in the future. If you’ve recently been diagnosed with breast cancer, your doctor may prescribe a combination of these treatment approaches depending on several factors, including the type and stage of your cancer.
Some of the very first drugs that were used against breast cancer — a disease that the National Breast Cancer Foundation reports afflicts 1 in 8 American women — are a class of drugs called anti-estrogen therapies. (They’re also sometimes referred to as hormone or endocrine therapies.) At the newer end of the spectrum are immunotherapies — cutting-edge treatments that leverage the body’s immune system to eradicate cancer cells.
[See: A Tour of Mammographic Screenings During Your Life.]
As with virtually every treatment currently available, both anti-estrogen drugs and immunotherapies can cause side effects in patients.
Anti-Estrogen Therapies
The American Cancer Society reports that about two-thirds of breast cancers are hormone-receptor positive, meaning that they use hormones — specifically estrogen and progesterone — to grow. “For these cancers, high estrogen levels help the cancer cells grow and spread,” the ACS reports. Therefore, hormone therapies either reduce the amount of estrogen circulating in the body or block it from adhering to cancer cells, thereby stifling the tumor’s growth.
Anti-estrogen therapies are typically delivered as a daily pill and are often used in combination with surgery to reduce the risk of cancer returning. The American Cancer Society reports that hormone therapies may also be started prior to surgery, and a course of treatment typically lasts for at least five years, sometimes stretching to 10.
There are two main types of hormone therapies currently in use:
— Selective estrogen receptor modulators, which block hormones from attaching to cancer cells. Tamoxifen, which was introduced in the 1960s, is the most common example of SERMs.
— Aromatase inhibitors, which inhibit the action of the enzyme aromatase that’s integral to the production of estrogen in the body.
SERM therapies are typically given to pre-menopausal women while AIs are typically prescribed to post-menopausal women, says Dr. Raquel Reinbolt, assistant professor of internal medicine at The Ohio State University Wexner Medical Center. Because these drugs affect hormones, side effects often include symptoms associated with menopause: Hot flashes, mood swings, night sweats, osteoporosis, vaginal discharge and vaginal dryness are among the most common. “Tamoxifen has a small risk of blood clots and a small risk of endometrial cancer,” Reinbolt says, so she recommends that patients taking this medication have an annual gynecological exam.
Dr. Sagar Sardesai, assistant professor of medicine at the Stephanie Spielman Comprehensive Breast Cancer at the Wexner Medical Center, adds that there’s a small risk of uterine cancer in patients taking tamoxifen — about “1 percent or 1.5 percent depending on the study you’re looking at.” He adds the risk of blood clots in the legs is the same as for women taking birth control pills — about 5 percent.
[See: 7 Innovations in Cancer Therapy.]
Common side effects of AIs — and there are currently three AIs approved for use — revolve around the bones, joints and muscles. Some patients — about 30 percent, according to Sardesai — experience joint pain or achy muscles while taking the drug. Those aches “tend to get better as women stay on this drug. The body finds a new equilibrium as it gets used to the drug,” and the achiness will subside over time, he says. In the meantime, anti-inflammatory medications such as Tylenol and aerobic exercise such as brisk walking and even yoga can help reduce joint pain associated with aromatase inhibitors. “AIs do not cause arthritis, but they can worsen pain in patients who have arthritis,” he says.
Because aromatase inhibitors can impact bone density, Reinbolt recommends that patients have a bone densitometry scan every two years. This is a form of X-ray that measures bone loss. Sardesai says taking AIs increases a woman’s risk of bone fractures, on the order of about 7 percent, but that can grow to 12 to 14 percent if she stays on the drug for 10 years.
These drugs also carry a slight risk, “about 2 percent of absolute risk” Sardesai says, of cardiovascular problems, as estrogen is involved in maintaining heart health. They may also cause a condition called “endo-brain,” where endo is short for endocrine. “Endo-brain is like chemo-brain,” Sardesai says, which is a mental fogginess that can result from chemotherapy. “Endo-brain can lead to word-finding problems,” where you’re searching for the right word and it just won’t come. It can also “affect cognitive processing,” which may impact your ability to complete simple math problems or other mental tasks that involve numbers. This condition tends to build up over time, so patients on these drugs for shorter periods are unlikely to experience endo-brain, and it’s a relatively rare side effect.
Sardesai says that if you’re having side effects with one aromatase inhibitor, speak with your doctor. You may have better results and fewer side effects with one of the other drugs.
Immunotherapies
Although immunotherapies are not currently considered the standard of care, they are carefully being investigated and could become the future of cancer treatment. They are available to some breast cancer patients via clinical trials.
“Immunotherapies are a novel way of fighting cancer in which we’re not trying to kill the cancer by direct effect,” Sardesai says. Rather, these newer treatments “unmask the cancer or make it more exposed to your immune cells.” The body’s own defense system kicks in to find and kill the cancer without the use of potentially toxic medications. “Immune therapies are usually more tolerable than chemo. They’re not killing cancer cells, so they’re also not killing healthy tissues either, so there’s no hair loss. Fatigue and nausea, which are the traditional chemotherapy side effects, are not a big deal” with immunotherapies in most patients, Sardesai says.
However, in some cases, “your immune system can go overboard. It’s overstimulated and starts attacking healthy tissue,” which is similar to what happens with autoimmune diseases, Sardesai says. Experiencing side effects from immunotherapy is “not as common as with chemotherapy where more than half of patients will have multiple side effects,” he says. But there are still some potential issues, some of which can be severe.
[See: What Not to Say to a Breast Cancer Patient.]
“The most common side effects are skin rashes, skin dryness and itching,” which can impact between 30 and 50 percent of patients on immunotherapies, he says. About 25 percent of patients will experience some level of fatigue. “The rest of the side effects are not that common, in the range of 5 percent or less of patients will experience these more severe side effects that can affect your quality of life. Things like severe diarrhea, colitis and inflammation of the large intestine, liver, kidneys or lungs and even inflammation of the brain have been seen in some cases. Some of these can be very serious,” Sardesai says. Steroids are typically prescribed to suppress these adverse immune responses, but steroids can also bring their own side effects. Therefore, as with any treatment, your doctor will need to carefully consider the cost verses benefits.
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What Are the Side Effects of Anti-Estrogen Drugs and Immunotherapies? originally appeared on usnews.com
